The XUART controller is a core we have included in the FPGA, as well as a userspace application called xuartctl for accessing these UARTs. Rather than using a kernel driver with the standard serial interface, we have implemented the XUARTs with features to simplify application development. The XUARTs allow you to easily use arbitrary baud rates, nonstandard modes such as DMX or 9n1, and they allow a very low latency operation. The XUART layer also uses the very low overhead TCP layer which allows you to transport serial over the network without writing any code.
The simplest example to get started is to define the port with:
xuartctl --server --port=1 --speed=115200
This will return "ttyname=/dev/pts/0", or a higher pts number. You can use this /dev/pts/# device to access the UART, but note that the pts device number can change based on other ssh, telnet or other processes. See this section for a sample script to setup the XUARTs with a predictable device name.
For more information and detailed usage, see the xuartctl page.